Banded Jawfish, Opistognathus macrognathus
Banded Jawfish, Opistognathus macrognathus, Male. Fish caught from coastal waters off West Palm Beach, Florida, May 2025. Length: 9.8 cm (3.9 inches). Catch, photograph and identification courtesy of James Lafontaine, Long Island, New York.
The Banded Jawfish, Opistognathus macrognathus, is a member of the Jawfish or Opistognathidae Family, that is also known as the Longjaw Jawfish and the Spotfin Jawfish and in Mexico as guardián and guardián bocón. Globally, there are forty-three species in the genus Opistognathus, of which thirteen are found in Mexican waters, six in the Atlantic and seven in the Pacific Ocean.
The Banded Jawfish have an elongated compressed tapering body with a large bulbous head. Their head and body and tan, the lower head and belly are whitish, and they are covered with a network of dark lines. The mid-body has a row of five or six dark blotches and another row on the upper back extending onto the dorsal fin base. The pectoral fins are covered with numerous dark specs. They have a black spot on the upper half of the dorsal fin between the sixth and ninth spines. The interior of the mouth is dark except for an oblong pale bar below each tooth patch at the upper rear. They are sexually dimorphic. Males have a long upcurved extension of the maxillary bone marked with black bands; females have a simple black band at the corner of their mouth. Their eyes are large and set high on the head and their mouth is large and terminal that extends to the rear of the eyes and is equipped with 1 to 3 teeth on the roof. They have simple nostril cirri. Their anal fin has 3 spines and 14 to 16 rays and a long base; their caudal fin is rounded; their dorsal fin has 11 spines and 16 or 17 rays and a long base; and, their pelvic fins are short and have 1 spine and 5 rays with the outer 2 being strong and unbranched and the inner 3 weaker and branched and occur after the pelvic fins. They have 31 to 43 gill rakes. They are covered with smooth small scales which are absent from the head. Their lateral line is only on the front half of the body.
The Banded Jawfish is found within sandy substrate adjacent to coral reefs. They prey upon crabs, fishes and gastropods. They reside in burrows which it enters tail first, at depths up to 44 m (145 feet). They reach a maximum of 20 cm (7.9 inches) in length. Unhatched fish are mouth brooded by the males and juveniles are guarded by both parents. Their larval stage is short, and the juveniles are prone to predation, including the invasive Red Lionfish, Pterois volitans, and they utilized burrowing to avoid predation. Dusky Jawfish is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, diet, growth, habitat, longevity, movement patterns, and reproduction.
The Banded Jawfish can be confused with the Dusky Jawfish, Opistognathus whitehursti (mottled body with dark specs; anal, caudal and dorsal fins with rows of pale spots), the white background, white top jaw with a black stripe) and the Mottled Jawfish, Opistognathus maxillosus (four dorsal spots; double white blotch separated by brown at the base of the caudal fin) and the Yellowmouth Jawfish, Opistonathus nothus (head covered with brown spots, top jaw with black stripe, dorsal fin with rows of small spots).
The Banded Jawfish is a resident of Mexican waters of the Atlantic Ocean being found from Veracruz to Scorpion (Alacranes) Reef along the northern Yucatán Peninsula in the Gulf of Mexico.
From a conservation perspective the Banded Jawfish is currently considered to be of Least Concern, with stable, widely distributed populations. They are small in stature and of limited interest to most. They are utilized by the aquarium trade but only at a very nominal level.